From the Super Mario Wiki
The Hard Court is a tennis court appearing in all Mario Tennis games. It is the default court, and is the court used in the Mushroom Cup in Mario Tennis and Mario Power Tennis. In the Game Boy games, the Hard Court is used by the Junior Rank players of the Royal Tennis Academy. In all games, it has a strong bounce with a normal speed. It is blue (green in Mario Tennis) and available in the exhibition mode of all games by default. Hard courts are the most commonly used tennis courts in real life.
Mario Tennis (Nintendo 64)
In the Nintendo 64 game Mario Tennis, the court is described as "A standard composite court with average ballspeed." The court's statistics state that it has normal ball speed and a strong bounce. It is a good court for beginners and is the most commonly used court.
Mario Tennis (Game Boy Color)
In the Game Boy Color counterpart Mario Tennis, the Hard Court is the court used by the Junior Ranked players as it is an easy course to use. Beating the Junior Rank grants the player the Senior Rank, where matches are then played on the Clay Court. It has the same bounce and ball speed as it's 64 counterpart.
Mario Power Tennis
The Hard Court appears in Mario Power Tennis again as a court with high bounce and normal ball speed. This time, it is one of the courts in Peach Dome. It is used for the main court of the Mushroom Cup, and can be displayed in different daylight settings.
Mario Tennis: Power Tour
Mario Tennis Open
The hard court appears as one of the Mario Stadium Courts. It is described as being a "Legendary court revered by top players." It is used in the first round of the Champions Cup. It has an alternative called Mushroom Valley that has the same ball speed and bounce and is played in the Mushroom Cup.